Crew-4 docking
A SpaceX Crew Dragon spacecraft docks with the ISS April 27, less than 16 hours after liftoff from Florida. Credit: NASA TV

WASHINGTON — A Crew Dragon spacecraft docked with the International Space Station with a new set of American and European astronauts April 27.

The Crew Dragon spacecraft Freedom docked with the station at 7:37 p.m. Eastern. Hatches separating the spacecraft and station opened about an hour and a half later.

The docking took place more than half an hour ahead of schedule and less than 16 hours after a Falcon 9 launched the spacecraft from the Kennedy Space Center. That transit time is the shortest yet for a Crew Dragon mission, although Soyuz spacecraft frequently arrive at the station within a few hours of launch.

That short transit was largely a matter of luck. “It’s just the orbital mechanics of where the ISS is and where it’s coming over Florida” for the launch, said Jessica Jensen, vice president of customer operations and integration at SpaceX, at a postlaunch briefing. That varies on a day-by-day basis, changing the transit times by 10 to 20 hours. “We’re not changing anything in the way we do our operations with NASA.”

The quick rendezvous was fortunate, added Steve Stich, NASA commercial crew program manager, since it avoided conflicts with a Russian spacewalk scheduled for April 28. Cosmonauts Oleg Artemyev and Denis Matveev will perform their second spacewalk in as many weeks to continue work to set up a European robotic arm on the Nauka module.

The Crew-4 astronauts — NASA’s Kjell Lindgren, Bob Hines, Jessica Watkins and the European Space Agency’s Samantha Cristoforetti — will start work to take over station operations from the Crew-3 astronauts, who have been on the station since mid-November. That handover will take about five days.

The Crew-3 astronauts — NASA’s Raja Chari, Thomas Marshburn, Kayla Barron and ESA’s Matthias Maurer — will return to Earth next week on the Crew Dragon spacecraft Endurance. Stich said that undocking is tentatively planned for May 4, with a splashdown off the coast of Florida May 5 “if the weather’s good.”

Weather was a complication for the return of the Crew Dragon spacecraft Endeavour on the Ax-1 mission earlier this month, requiring the four private astronauts to spend an extra week on the space station, nearly twice as long as originally planned. NASA officials previously said they want Crew-3 to undock by May 10 to avoid a period of unfavorable sun angles that would hinder dockings and undockings for about a week and a half.

Jeff Foust writes about space policy, commercial space, and related topics for SpaceNews. He earned a Ph.D. in planetary sciences from the Massachusetts Institute of Technology and a bachelor’s degree with honors in geophysics and planetary science...